In general, various heat treatments, such as deposition, pattern etching, oxidation diffusion and refining, are repeatedly carried out with respect to a semiconductor wafer to produce a desired semiconductor device. With the increase of wafer size, there is a tendency to often use a so-called single wafer processing heat treatment system which can more easily obtain the inplane uniformity of treatment than that in a batch heat treatment system. The single wafer processing heat treatment system is disclosed in Japanese Patent Laid-Open Nos. 5-51294 and 9-219369.
For example, the heat treatment system of this type has a mounting table for supporting thereon a semiconductor wafer, a heating lamp serving as a wafer heating means, a resistance heater and so forth, in an evacuated processing vessel. When a heat treatment is carried out, while a predetermined required gas is supplied from a shower head portion provided on the ceiling portion of the vessel or the like, the pressure in the processing vessel is maintained at a predetermined process pressure, and a wafer is heated and maintained at a predetermined process temperature to carry out deposition and so forth.
In this case, if the shower head portion and the wall face of the processing vessel are excessively heated, e.g. when deposition is carried out, an undesired film and a reaction by-product adhere to the wall face. Therefore, the shower head portion and the wall face of the processing vessel are cooled by a cooling mechanism to prevent the temperature thereof from excessively rising. If a heating lamp is used as a heating means, the temperature of a partition wall of a lamp chamber for housing therein the heating lamp excessively rises, so that a cooling mechanism is provided for cooling this.
By the way, a chiller for producing and circulating a fluid at a constant temperature is generally used as the cooling mechanism. The chiller has a very large heat exchange system for cooling a heating medium to a predetermined temperature and for circulating the medium to a structure to be cooled.
The chiller has the advantage of easily controlling the temperature of the medium. However, since the chiller is very large as described above, there is a problem in that equipment costs do not only rise, but the installation space (foot print) is also too large.